1. Field of the Invention
The present invention pertains to the storage of information, and particularly to automated cartridge handling systems such as cartridge libraries which store cartridges or cassettes of magnetic tape.
2. Related Art and other Considerations
The economic and compact storage of information is increasingly important in the computer industry, particularly so as the computer unleashes new potentials in numerous fields such as audio visual and/or multimedia.
In the early days of computers, information requiring storage could be transmitted from a computer to a tape drive, whereat the information was magnetically recorded on or read from a large reel of tape. Upon completion of an operation of recording on the tape, for example, the reel would be removed manually from the tape drive and mounted in a rack. Another reel from the rack could then be manually mounted, if necessary, in the drive for either an input (tape reading) or output (recording to tape) operation.
Eventually it became popular to enclose magnetic tape in a cartridge, the cartridge being considerably smaller than the traditional tape reels. While many persons are familiar with tape cartridges of a type which can be loaded into a "tape deck" for reproduction of audio information (e.g., music), it is not as commonly realized that similar cartridges, although of differing sizes, can be used to store such information as computer data. For years now magnetic tape cartridges have proven to be an efficient and effective medium for data storage, including but not limited to computer back-up.
Large computer systems have need to access numerous cartridges. To this end, automated cartridge handling systems or libraries for cartridges have been proposed for making the cartridges automatically available to the computer. Many of these automated libraries resemble juke boxes. Typically, prior art automated cartridge libraries have an array of storage positions for cartridges, one or more tape drives, and some type of automated changer or cartridge engagement/transport mechanism for picking or gripping a cartridge and moving the cartridge between a storage position and the tape drive.
The following United States patents, all commonly assigned herewith and incorporated herein by reference, disclose various configurations of automated cartridge libraries, as well as subcomponents thereof (including cartridge engagement/transport mechanisms and storage racks or magazines for housing cartridges):
U.S. Pat. No. 4,984,106 to Herger et al., entitled "CARTRIDGE LIBRARY SYSTEM AND METHOD OF OPERATION THEREOF"; PA1 U.S. Pat. No. 4,972,277 to Sills et al., entitled "CARTRIDGE TRANSPORT ASSEMBLY AND METHOD OF OPERATION THEREOF"; PA1 U.S. Pat. No. 5,059,772 to Younglove, entitled "READING METHOD AND APPARATUS FOR CARTRIDGE LIBRARY"; PA1 U.S. Pat. No. 5,103,986 to Marlowe, entitled "CARTRIDGE RACK"; and, PA1 U.S. Pat. Nos. 5,237,467 and 5,416,653 to Marlowe, entitled "CARTRIDGE HANDLING APPARATUS AND METHOD WITH MOTION-RESPONSIVE EJECTION". PA1 U.S. Pat. No. 5,498,116 to Woodruff et al., entitled "ENTRY-EXIT PORT FOR CARTRIDGE LIBRARY". PA1 U.S. Pat. No. 5,487,579 to Woodruff et al., entitled "PICKER MECHANISM FOR DATA CARTRIDGES". PA1 U.S. Pat. No. 5,718,339 to Woodruff et al., entitled "CARTRIDGE RACK AND LIBRARY FOR ENGAGING SAME".
Some cartridge libraries have, on a front panel of their housing, a special door or access (sometimes known as an "entry/exit port") through which an operator can manually insert a cartridge for loading into the inventory of the library without opening the entire front panel or main door of the library. For example, in the Exabyte EXB-120 cartridge library, an entry/exit cartridge holder (which held a single cartridge) reciprocated between the entry/exit port at the front panel of the housing and a temporary station in the interior of the library housing. When the entry/exit cartridge holder arrived at the entry/exit port, the entry/exit cartridge holder shoved the cartridge through the entry/exit port door so that the sole cartridge carried thereby partly protruded from the front panel of the library housing, so that an operator could grasp the protruding cartridge. When the entry/exit cartridge holder was at the temporary station, a cartridge picker mechanism could move a cartridge from magazines (or a drive) in the library to the temporary station, or a cartridge newly entered at the temporary station to a magazine (or drive).
Other schemes of entry/exit are also known. For example, in U.S. Pat. No. 5,498,116, an entry/exit transport arm travels and pivots in an entry/exit transport plane, and is extensible in such plane. As another example, U.S. Pat. No. 4,779,151 to Lind et al. shows a receptacle-type scheme for introduction of new cartridges, in which rotary loading and unloading mechanisms are provided in the housing of a cartridge library.
Preferably employment and operation of entry/exit facilities should not interfere with the on-going operation of a cartridge library. In other words, while the entry/exit port is being utilized, the remainder of the cartridge library should remain operational. Moreover, the continued operation of the remainder of the cartridge library should not have the potential of injuring an operator who is using the entry/exit port.
What is needed, therefore, and an object of the present invention, is a cartridge library having an entry/exit port which permits continued and safe use of the remainder of the cartridge library.